555-million year old human ancestor discovered

New Delhi : Well, it looks like we all came from a critter!

The scientists have discovered one of the earliest ancestors of life – a minuscule worm-like creature – that lived on the seafloor 555-million years ago.

The critter has been given a scientific name Ikaria Wariootia. Researchers led by geologists at the University of California (UC) Riverside have identified the critter as the first known bilaterian, an organism with a front and back, symmetrical sides and front and back openings with a gut in between.

Bilaterian plays an important role in understanding the evolution of whole animal life on the planet. 

"It's the oldest fossil we get with this type of complexity," UC Riverside geology professor Mary Droser said in a press release.

Earlier, the organisms resembled sponges and had no mouth and gut, hence not bilaterian. The organism then was simple with only basic sensory inhibitions.

The evidence of such organisms was found in burrows, ie, the patterns left behind by such organisms on surfaces owing to their movements.

As 3D scanning gets more sophisticated, a dozen more such burrows have been in South Australia. "This is what evolutionary biologists predicted," Mary Droser said in a statement.

"It's really exciting that what we have found lines up so neatly with their prediction."

The findings of the research have been published in Proceedings of the National Academy of Sciences Monday.

The Ikaria is very small in size, with a maximum length of 6.7 millimetres and a maximum width of 2.4 millimetres. 

Researchers posit that their largest size did not exceed 7 millimetres, making them as big as a grain of rice.

The shape left behind by them in the burrows explains their movement, which is somewhat similar to contemporary worms, who use their muscles to trigger movement.